1. Field of the Invention
The present invention relates to a technology for detecting a liquid discharge failure in an inkjet recording apparatus.
2. Description of the Related Art
Some types of apparatuses, such as a liquid measurement apparatus disclosed in Japanese Patent Application Laid-open No. 2006-47235, include a laser-beam generating unit, and detect a shadow of the droplet projected by the laser beam. The laser-beam generating unit emits a laser beam in a direction that intersects with a direction in which a droplet of liquid is discharged.
The liquid measurement apparatus disclosed in Japanese Patent Application Laid-open No. 2006-47235 includes a laser-beam generating unit, a photoelectric conversion unit, and a signal processing unit. The laser-beam generating unit generates a laser beam toward a passage of a droplet of liquid. The photoelectric conversion unit converts an optical intensity of the laser beam into an electric signal, which is then processed by the signal processing unit. The signal processing unit stores therein a relational expression between optical intensity expressed in electric signal and weight of droplet of liquid. The liquid measurement apparatus calculates a weight of a droplet by referring to the relational expression for an optical intensity expressed in an electric signal fed from the photoelectric conversion unit. The liquid measurement apparatus further includes a beam converging unit that converges a laser beam. A droplet of liquid is discharged through a liquid discharging head toward the converged beam. Accordingly, spatial resolution is increased, resulting in an increase in signal strength.
However, in such a liquid measurement apparatus, when liquid is to be discharged from two or more positions, it is necessary to change the position to which the laser beam converges by, for example, moving the beam converging unit. Accordingly, this type of liquid measurement apparatus is disadvantageous because it requires a drive mechanism to move the beam converging unit. Provision of the drive mechanism increases the costs makes the overall configuration complex.